STZ-Vortex model: The key to understand STZ percolation and shear banding in metallic glasses

Şopu, Daniel

doi:10.1016/j.jallcom.2023.170585

Cited by 4 publications

(1 citation statement)

References 136 publications

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“…In addition, the SB evolution path has been reported to be strongly conjugated to the primary shear stress profile, as the maximum shear stress reflects the driving force for SB expansion [140]. Last but not least, the vortex field around STZs in BMGs has also been investigated via molecular dynamics [141]. The results indicate that a rotation field is provided from the quadrupolar strain distribution around an STZ, revealing the propagating paths of SBs, their interaction and their multiplication.…”

Section: Figure 21mentioning

confidence: 99%

A Review on the Adiabatic Shear Banding Mechanism in Metals and Alloys Considering Microstructural Characteristics, Morphology and Fracture

Karantza,

Manolakos

2023

Metals

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The current review work studies the adiabatic shear banding (ASB) mechanism in metals and alloys, focusing on its microstructural characteristics, dominant evolution mechanisms and final fracture. An ASB reflects a thermomechanical deformation instability developed under high strain and strain rates, finally leading to dynamic fracture. An ASB initially occurs under severe shear localization, followed by a significant rise in temperature due to high strain rate adiabatic conditions. That temperature increase activates thermal softening and mechanical degradation mechanisms, reacting to strain instability and facilitating micro-voiding, which, through its coalescence, results in cracking failure. This work aims to summarize and review the critical characteristics of an ASB’s microstructure and morphology, evolution mechanisms, the propensity of materials against an ASB and fracture mechanisms in order to highlight their stage-by-stage evolution and attribute them a more consecutive behavior rather than an uncontrollable one. In that way, this study focuses on underlining some ASB aspects that remain fuzzy, allowing for further research, such as research on the interaction between thermal and damage softening regarding their contribution to ASB evolution, the conversion of strain energy to internal heat, which proved to be material-dependent instead of constant, and the strain rate sensitivity effect, which also concerns whether the temperature rise reflects a precursor or a result of ASB. Except for conventional metals and alloys like steels (low carbon, stainless, maraging, armox, ultra-high-strength steels, etc.), titanium alloys, aluminum alloys, magnesium alloys, nickel superalloys, uranium alloys, zirconium alloys and pure copper, the ASB propensity of nanocrystalline and ultrafine-grained materials, metallic-laminated composites, bulk metallic glasses and high-entropy alloys is also evaluated. Finally, the need to develop a micro-/macroscopic coupling during the thermomechanical approach to the ASB phenomenon is pointed out, highlighting the interaction between microstructural softening mechanisms and macroscopic mechanical behavior during ASB evolution and fracture.

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Section: Figure 21mentioning

confidence: 99%

A Review on the Adiabatic Shear Banding Mechanism in Metals and Alloys Considering Microstructural Characteristics, Morphology and Fracture

Karantza,

Manolakos

2023

Metals

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Controlling the Glassy State toward Structural and Mechanical Enhancement: Additive Manufacturing of Bulk Metallic Glass Using Advanced Laser Beam Shaping Technology

Hadibeik,

Ghasemi‐Tabasi,

Burn

et al. 2023

Adv Funct Materials

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Bulk metallic glasses (BMGs) offer exceptional physical/mechanical properties enabling them to be highly desirable for a varietyof applications. Laser powder bed fusion (LPBF) has great promise for producing large and intricate BMG structures. However, using non‐optimal energy distribution in current additive manufacturing machines leads to extensive reheating of previously solidified layers. As a result, the mechanical characteristics can be significantly impacted by structural relaxation and partial crystallization. Here, a tunable advanced laser beam shaping technology is employed to overcome the difficulties originating from non‐optimal energy distribution in current additive manufacturing machines. This study fabricates fully amorphous/dense BMG samples using the shaped laser beam and established optimized atomic‐scale short‐and medium‐range ordering along with improved yield/fracture compressive strength. Formation of a shallow and wide melting pool geometry using the beam shaping allows to increase hatching distances to better control the thermal history introducing improved amorphicity and rejuvenation. This higher rejuvenation and disordering allow for increased atomic mobility, which facilitates the creation and spread of shear bands, thus enhancing the mechanical strength and ductility of the material. The current work demonstrates that BMG parts can be fabricated using flexible beam‐shaping technology allowing to go beyond the capabilities of state‐of‐the‐art additive manufacturing techniques.

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Mechanism of chip segmentation transition from shear slip to shear fracture of Zirconium-based bulk metallic glass in mechanical machining

Ding,

Zhang,

Wang

et al. 2024

Journal of Materials Research and Technology

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STZ-Vortex model: The key to understand STZ percolation and shear banding in metallic glasses

Cited by 4 publications

References 136 publications

A Review on the Adiabatic Shear Banding Mechanism in Metals and Alloys Considering Microstructural Characteristics, Morphology and Fracture

A Review on the Adiabatic Shear Banding Mechanism in Metals and Alloys Considering Microstructural Characteristics, Morphology and Fracture

Controlling the Glassy State toward Structural and Mechanical Enhancement: Additive Manufacturing of Bulk Metallic Glass Using Advanced Laser Beam Shaping Technology

Mechanism of chip segmentation transition from shear slip to shear fracture of Zirconium-based bulk metallic glass in mechanical machining

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